This invention pertains to rotary storage devices wherein data is stored in parallel tracks and more particularly to a sector identification technique which eliminates the need to read an identification field for each sector while identifying and accommodating random defective sectors.
In rotating memory devices, the configuration of the sectors into which the tracks of information are partitioned each employs an identification (ID) field with a preceding sync field and a trailing cyclic redundancy check (CRC) or other check field and a data field with its preceding sync field and trailing error correction code (ECC). The use of an error correction code makes the writing and retrieval of data more reliable and enables higher track and bit densities to be achieved with the same reliability. However, to realize the benefits of the use of an ECC with data, the reading of the ID field must be done with the same reliability. This would indicate that instead of a simple parity or cyclic redundancy check, the ID field must be read with the same reliability as the data field using an ECC of some substantial sophistication. To provide the same reliability, the same level of error recovery should protect both ID and data fields. If the fields are combined to achieve this result, the recording technique must be one that does not require one revolution to read the ID and a second revolution to record data since such an extended time period would degrade the overall performance of the storage device.